U.S. patent number 11,064,509 [Application Number 16/720,014] was granted by the patent office on 2021-07-13 for methods, base station, infrastructure node and communications terminal.
This patent grant is currently assigned to SONY CORPORATION. The grantee listed for this patent is Sony Corporation. Invention is credited to Jussi Tapani Kahtava, Brian Alexander Martin, Hideji Wakabayashi, Yuxin Wei.
United States Patent |
11,064,509 |
Martin , et al. |
July 13, 2021 |
Methods, base station, infrastructure node and communications
terminal
Abstract
A method of transmitting data from a first communications
terminal to one or more second communications terminals includes
receiving from an infrastructure equipment forming part of a
wireless communications network an indication identifying a
predetermined pattern of communications resources of a wireless
access interface. The wireless access interface provides plural
communications resources divided into time divided units. The
method also includes transmitting the data in some or all of the
predetermined pattern of communications resources to one or more of
the second communications terminals in accordance with device to
device communications. The predetermined pattern of communications
resources is one of plural patterns of communications resources of
the wireless access interface for plural of the time divided units.
The plural patterns of communications resources are predetermined
for a reduction in latency when transmitting the data from the
first communications terminal and/or reducing in signalling
overhead required to transmit the data.
Inventors: |
Martin; Brian Alexander
(Basingstoke, GB), Wei; Yuxin (Basingstoke,
GB), Kahtava; Jussi Tapani (Basingstoke,
GB), Wakabayashi; Hideji (Basingstoke,
GB) |
Applicant: |
Name |
City |
State |
Country |
Type |
Sony Corporation |
Tokyo |
N/A |
JP |
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Assignee: |
SONY CORPORATION (Tokyo,
JP)
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Family
ID: |
1000005676836 |
Appl.
No.: |
16/720,014 |
Filed: |
December 19, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20200128563 A1 |
Apr 23, 2020 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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15773214 |
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10517107 |
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PCT/EP2016/075245 |
Oct 20, 2016 |
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Foreign Application Priority Data
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Nov 13, 2015 [EP] |
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15194635 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
72/042 (20130101); H04L 5/0053 (20130101); H04W
76/14 (20180201); H04W 72/121 (20130101); H04W
72/0446 (20130101) |
Current International
Class: |
H04W
72/12 (20090101); H04L 5/00 (20060101); H04W
76/14 (20180101); H04W 72/04 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2015/143170 |
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Sep 2015 |
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WO |
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WO-2015143170 |
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Sep 2015 |
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WO |
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2015/152785 |
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Oct 2015 |
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WO |
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WO-2015152785 |
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Oct 2015 |
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WO |
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2017/001223 |
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Jan 2017 |
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WO |
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Other References
"Discussion on V2V Scheduling, Resource Pools and Resource
Patterns", Ericsson, 3GPP TSG RAN WG1 Meeting #82bis, R1-155909,
Oct. 2015, 6 pages. cited by applicant .
Harri Holma, et al., "L TE for UMTS OFDMA and SC-FDMA Based Radio
Access", John Wiley & Sons Limited, Jan. 2010, 8 pages. cited
by applicant .
LTE; "Evolved Universal Terrestrial Radio Access (E-UTRA); Medium
Access Control (MAC) protocol specification", 3GPPTS 36.321, ETSI
TS 136 321 V12.5.0, 2015, 79 pages. cited by applicant .
International Search Report dated Jan. 16, 2017 in
PCT/EP2016/075245. cited by applicant .
European Search Report dated Apr. 1, 2019, issued in corresponding
EP Application No. 16784502.3, 6 pages. cited by applicant .
Office Action dated Sep. 10, 2019, issued in corresponding European
Application No. 16784502.3, 8 pages. cited by applicant.
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Primary Examiner: Lo; Diane L
Attorney, Agent or Firm: Xsensus LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a continuation of U.S. application Ser.
No. 15/773,214, filed May 3, 2018, which is based on PCT filing
PCT/EP2016/075245, filed Oct. 20, 2016, which claims priority to EP
15194635.7, filed Nov. 13, 2015, the entire contents of each are
incorporated herein by reference.
Claims
The invention claimed is:
1. A method, comprising: receiving, by a first communications
terminal from an infrastructure equipment of a wireless
communications network, an indication identifying a predetermined
pattern of communications resources of a wireless access interface,
the wireless access interface providing a plurality of
communications resources divided in time and the predetermined
pattern of communications resources being allocated by the
infrastructure equipment to the first communications terminal
across multiple scheduling control periods; and transmitting, by
the first communications terminal to a second communications
terminal, the data in at least some communications resources of the
predetermined pattern of communications resources, wherein the
predetermined pattern of communications resources is one of a
plurality of patterns of communications resources of the wireless
access interface.
2. The method as claimed in claim 1, wherein the plurality of
patterns of communications resources are pre-configured in any of
the first communications terminal, the second communications
terminal and the infrastructure equipment.
3. The method as claimed in claim 1, further comprising: receiving,
by the first communications terminal from the infrastructure
equipment, another indication of the plurality of patterns of
communications resources, wherein the another indication is
transmitted by the infrastructure equipment for receipt by the
first communications terminal and the second communications
terminal.
4. The method as claimed in claim 3, wherein the receiving the
another indication includes receiving the another indication a
plurality of times, and the infrastructure equipment changes the
plurality of patterns of communications resources between each
transmission of the another indication.
5. The method as claimed in claim 1, wherein the predetermined
pattern of communications resources identifies different
communications resources in different time divided units.
6. The method as claimed in claim 1, wherein the receiving the
indication comprises receiving a scheduling assignment message from
the second communications terminal, the infrastructure equipment
having allocated a plurality of the patterns for communications
resources to the first communications terminal and the second
communications terminal.
7. The method as claimed in claim 1, wherein the transmitting, by
the first communications terminal to the second communications
terminal, is performed via device to device communications.
8. Circuitry for a communications terminal, the circuitry
comprising: reception circuitry configured to receive, from an
infrastructure equipment of a wireless communications network, an
indication identifying a predetermined pattern of communications
resources of a wireless access interface, the wireless access
interface providing a plurality of communications resources divided
in time and the predetermined pattern of communications resources
being allocated by the infrastructure equipment to the
communications terminal across multiple scheduling control periods;
and transmission circuitry configured to transmit, to another
communications terminal, the data in at least some communications
resources of the predetermined pattern of communications resources,
wherein the predetermined pattern of communications resources is
one of a plurality of patterns of communications resources of the
wireless access interface.
9. The circuitry as claimed in claim 8, wherein the plurality of
patterns of communications resources are pre-configured in any of
the communications terminal, the another communications terminal
and the infrastructure equipment.
10. The circuitry as claimed in claim 8, wherein the reception
circuitry is further configured to receive, from the infrastructure
equipment, another indication of the plurality of patterns of
communications resources, and the another indication is transmitted
by the infrastructure equipment for receipt by the communications
terminal and the another communications terminal.
11. The circuitry as claimed in claim 10, wherein the reception
circuitry is configured to receive the another indication a
plurality of times, and the infrastructure equipment changes the
plurality of patterns of communications resources between each
transmission of the another indication.
12. The circuitry as claimed in claim 8, wherein the predetermined
pattern of communications resources identifies different
communications resources in different time divided units.
13. The circuitry as claimed in claim 8, wherein the reception
circuitry is further configured to receive a scheduling assignment
message from the another communications terminal, the
infrastructure equipment having allocated a plurality of the
patterns for communications resources to the communications
terminal and the another communications terminal.
14. The circuitry as claimed in claim 8, wherein the transmission
circuitry transmits the data to the another communications terminal
via device to device communications.
15. A communications terminal, comprising: processing circuitry
configured to: receive, from an infrastructure equipment of a
wireless communications network, an indication identifying a
predetermined pattern of communications resources of a wireless
access interface, the wireless access interface providing a
plurality of communications resources divided in time and the
predetermined pattern of communications resources being allocated
by the infrastructure equipment to the communications terminal
across multiple scheduling control periods; and transmit, to
another communications terminal, the data in at least some
communications resources of the predetermined pattern of
communications resources, wherein the predetermined pattern of
communications resources is one of a plurality of patterns of
communications resources of the wireless access interface.
16. The communications terminal as claimed in claim 15, wherein the
plurality of patterns of communications resources are
pre-configured in any of the communications terminal, the another
communications terminal and the infrastructure equipment.
17. The communications terminal as claimed in claim 15, wherein the
processing circuitry is further configured to receive, from the
infrastructure equipment, another indication of the plurality of
patterns of communications resources, and the another indication is
transmitted by the infrastructure equipment for receipt by the
communications terminal and the another communications
terminal.
18. The communications terminal as claimed in claim 17, wherein the
processing circuitry is configured to receive the another
indication a plurality of times, and the infrastructure equipment
changes the plurality of patterns of communications resources
between each transmission of the another indication.
19. The communications terminal as claimed in claim 15, wherein the
processing circuitry is further configured to receive a scheduling
assignment message from the another communications terminal, the
infrastructure equipment having allocated a plurality of the
patterns for communications resources to the communications
terminal and the another communications terminal.
20. The communications terminal as claimed in claim 15, wherein the
processing circuitry transmits the data to the another
communications terminal via device to device communications.
Description
TECHNICAL FIELD OF THE DISCLOSURE
The present disclosure relates to methods, base station,
infrastructure node and terminal, and more broadly considers
situations surrounding the allocation of resources in a mobile
telecommunications system.
BACKGROUND OF THE DISCLOSURE
The "background" description provided herein is for the purpose of
generally presenting the context of the disclosure. Work of the
presently named inventors, to the extent it is described in this
background section, as well as aspects of the description which may
not otherwise qualify as prior art or may not form part of the
state of the art at the time of filing, are neither expressly or
impliedly admitted as prior art or state of the art against the
present invention.
Mobile telecommunication systems, such as those based on the 3GPP
defined UMTS and Long Term Evolution (LTE) architecture, are able
to support more sophisticated services than simple voice and
messaging services offered by previous generations of mobile
telecommunication systems. For example, with the improved radio
interface and enhanced data rates provided by LTE systems, a user
is able to enjoy high data rate applications such as video
streaming and video conferencing on mobile communications devices
that would previously only have been available via a fixed line
data connection.
The demand to deploy fourth generation networks is therefore strong
and the coverage area of these networks, i.e. geographic locations
where access to the networks is possible, is increasing rapidly and
expected to continue to increase. However, although the coverage
and capacity of fourth generation networks is expected to
significantly exceed those of previous generations of
communications networks, there are still limitations on network
capacity and the geographical areas that can be served by such
networks. These limitations may, for example, be particularly
relevant in situations in which networks are experiencing high load
and high-data rate communications between communications devices,
or when communications between communications devices are required
but the communications devices may not be within the coverage area
of a network. In order to address these limitations, in LTE
release-12 the ability for LTE communications devices to perform
device-to-device (D2D) communications is introduced.
D2D communications allow communications devices that are in close
proximity to directly communicate with each other, both when within
and when outside of a coverage area or when the network fails. This
D2D communications ability allows communications devices that are
in close proximity to communicate with one another although they
may not be within the coverage area of a network. The ability for
communications devices to operate both inside and outside of
coverage areas makes LTE systems that incorporate D2D capabilities
well suited to applications such as public safety communications,
for example. Public safety communications require a high degree of
robustness whereby devices can continue to communicate with one
another in congested networks and when outside a coverage area.
Other types of relatively new protocols, features, arrangements or
sets thereof of mobile telecommunications systems include for
example relay node technology which can extend the coverage for
base station or another node for communicating with terminals, in
terms of throughput and/or geographical coverage. Small cells may
also be provided wherein a small cell can be controlled by a base
station or operate as a base station with a limited coverage
(either geographically or in the terminals accepted by the small
cell, e.g. only terminals associated with a specific
customer/company account may be able to connect to it). As a
result, a variety of technologies, some of them alternative and
other compatible technologies, can be now be used in a mobile
telecommunication system.
In parallel, the development of vehicle-related communications has
emerged and attracted a growing interest. These communications can
sometimes be called vehicle-to-everything (V2X) communications
which can refer to any one or combination of the following:
vehicle-to-vehicle (V2V) communications, vehicle-to-infrastructure
(V2I), vehicle-to-pedestrians (V2P) communications, vehicle-to-home
(V2H) communications and any other type of vehicle-to-something
communications. They enable a vehicle to communicate with its
environment, be it another vehicle, a traffic light, a level
(railroad) crossing, infrastructure equipment in the vicinity of a
road, a pedestrian, a cyclist, etc. In a typical V2I scenario, V2I
communications is used for collision prevention, driver alerting
and/or other intersection related activity. In this kind of
embodiment, the V2X-enabled terminal has to find out the relevant
Road Side Unit (RSU) to connect to and exchange information with.
More generally, this new set of technologies can enable a variety
of features such a convoying of vehicles, safety features,
environmental friendly car driving and/or management and can also
facilitate the operation of driverless/autonomous cars.
Whilst D2D communications techniques can provide an arrangement for
communicating between devices, D2D is generally targeting public
safety uses, so-called machine type communication (MTC)
applications--which tend to be low-throughput and high-latency
communications--or conventional terminals. As a result, they are
not designed to deal with low-latency communications required for
V2X communications. As an illustration, V2X systems can be required
to have a delay of less than 100 ms from an event to a
corresponding action. For example, from the moment a first car in
front of a second car suddenly brakes until the second car starts
braking as well, the time must be less than 100 ms in some
circumstances. This takes into account the time for the first
vehicle to detect the braking, signal the braking to other
vehicles, the second vehicle receiving the signal, processing the
signal to decide whether to take any actions, up to the moment the
second vehicle actually starts braking. Such a delay requirements
therefore does not leave much time for the first vehicle to signal
the situation to the other vehicles, including the second vehicle,
and the V2X communications should be carried out in a high
priority, high reliability and low-latency manner as much as
possible. A low priority may delay the communications more than
necessary, a low reliability may result in retransmissions being
carried out which also significantly increase the delay in the
transmissions while a high latency clearly increases the risk of
taking up too much of the time period allocated from an event to
the corresponding action.
SUMMARY OF THE DISCLOSURE
According to an example embodiment of the present technique there
is provided a method of transmitting data from a first
communications terminal to one or more second communications
terminals. The method comprises receiving from an infrastructure
equipment forming part of a wireless communications network an
indication identifying a predetermined pattern of communications
resources of a wireless access interface. The identifying
indication of the predetermined pattern of communications resource
may be for example a pointer, flag or bit map or any other message
identifying the predetermined or preconfigured communications
resources. The wireless access interface provides a plurality of
communications resources divided in time into a time divided units.
The method also comprises transmitting the data in some or all of
the predetermined pattern of communications resources to one or
more of the second communications terminals in accordance with
device to device communications. The predetermined pattern of
communications resources is one of a plurality of patterns of
communications resources of the wireless access interface for a
plurality of the time divided units. The plurality of patterns of
communications resources are predetermined so that there is a
reduction in a latency (transmission delay) when transmitting the
data from the first communications terminal and/or a reducing in
signalling overhead which is required to transmit the data.
In some embodiments the plurality of patterns of communications
resources are predetermined because the patterns of communications
resources are pre-configured into the construction of the
communications terminals and the infrastructure equipment. In other
embodiments the method includes transmitting from the
infrastructure equipment an indication of the plurality of patterns
of communications resources to the communications terminals
operating in a coverage area of the infrastructure equipment. The
indication may be transmitted on a broadcast channel.
The second terminal may for example act as a Road Side Unit, which
is performing D2D communications with the first communications
terminal. In one example therefore the second terminal requests and
is granted resources to support D2D communications with other
communications terminals such as the first terminal. The resources
are allocated by the infrastructure equipment by transmitting in
response to the request one or more identifying indications to the
plurality of predetermined patterns of communications resources to
the second terminal acting as an RSU. Since the plurality of
patterns of communications resources are predetermined and are
allocated for more than one time divided unit of the wireless
access interface, there is a reduction in transmission time for
data from the communications terminal and a reduction in signalling
overhead.
Various further aspects and features of the present technique are
defined in the appended claims.
The foregoing paragraphs have been provided by way of general
introduction, and are not intended to limit the scope of the
following claims. The described embodiments, together with further
advantages, will be best understood by reference to the following
detailed description taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the disclosure and many of the
attendant advantages thereof will be readily obtained as the same
becomes better understood by reference to the following detailed
description when considered in connection with the accompanying
drawings wherein like reference numerals designate identical or
corresponding parts, and wherein:
FIG. 1 provides a schematic diagram of a mobile communications
system according to an example of an LTE standard;
FIG. 2 illustrates an example system for communicating with at
least a terminal in a heterogeneous network;
FIG. 3 illustrates an example of a heterogeneous environment;
FIG. 4 illustrates an example route of a terminal associated with a
vehicle in a city environment comprising several Road Side Units
(RSU);
FIG. 5 illustrates a conventional decision process applied to
changing serving RSU;
FIG. 6 illustrates an example method of allocating resources;
FIG. 7 illustrates an example RSU having a plurality of remote
radio heads (RRH);
FIG. 8 illustrates an example graph representing a RSU network and
routes between the RSUs;
FIG. 9 illustrates another example graph representing a RSU network
and routes between the RSUs;
FIG. 10 illustrates another example method of allocating
resources;
FIG. 11 illustrates an example method of a terminal reporting
measurement information;
FIG. 12 illustrates another example method of a terminal reporting
measurement information;
FIG. 13 illustrates an example of allocating resources to a
terminal in the absence of a resource allocation request;
FIG. 14 illustrates an example of D2D resources allocation;
FIG. 15 illustrates an example comparison of a D2D resources
allocation with a resource allocation in accordance with the
present disclosure;
FIG. 16 illustrates an example method of allocating resources at an
infrastructure unit in the absence of a resource allocation request
from the terminal;
FIG. 17 illustrates an example method of communicating between a
terminal and one or more infrastructure nodes in the absence of
resource allocation request from the terminal;
FIG. 18 illustrates an example network with three RSUs and
resources allocated to each RSU for communications with the
terminals;
FIG. 19 illustrates an example method of allocating and
de-allocating resources in the absence of a resource allocation
requests from terminals;
FIG. 20 provides an example representation of a plurality of
sub-frames providing shared channel resources in which resource
patterns are allocated semi-persistently; and
FIG. 21 provides a flow diagram illustrating an example method of
allocating and de-allocating (releasing) resources in the absence
of a resource allocation requests from terminals.
DESCRIPTION OF EXAMPLE EMBODIMENTS
Hereinafter preferred embodiments of the present technique will be
described in detail with reference to the appended drawings. Note
that, in this specification and appended drawings, structural
elements that have substantially the same function and structure
can be denoted with the same reference numerals, and repeated
explanation of these structural elements may be omitted.
FIG. 1 provides a schematic diagram illustrating some basic
functionality of a conventional mobile telecommunications network,
using for example a 3GPP defined UMTS and/or Long Term Evolution
(LTE) architecture. The mobile telecommunications network/system
100 of FIG. 1 operates in accordance with LTE principles and which
may be adapted to implement embodiments of the disclosure as
described further below. Various elements of FIG. 1 and their
respective modes of operation are well-known and defined in the
relevant standards administered by the 3GPP (RTM) body, and also
described in many books on the subject, for example, Holma H. and
Toskala A [1]. It will be appreciated that operational aspects of
the telecommunications network which are not specifically described
below may be implemented in accordance with any known techniques,
for example according to the relevant standards.
The network 100 includes a plurality of base stations 101 connected
to a core network 102. Each base station provides a coverage area
103 (i.e. a cell) within which data can be communicated to and from
terminal devices 104. Data is transmitted from base stations 101 to
terminal devices 104 within their respective coverage areas 103 via
a radio downlink. Data is transmitted from terminal devices 104 to
the base stations 101 via a radio uplink. The uplink and downlink
communications are made using radio resources that are licensed for
use by the operator of the network 100. The core network 102 routes
data to and from the terminal devices 104 via the respective base
stations 101 and provides functions such as authentication,
mobility management, charging and so on. Terminal devices may also
be referred to as mobile stations, user equipment (UE), user
terminal, mobile terminal, mobile device, terminal, mobile radio,
and so forth. Base stations may also be referred to as transceiver
stations/nodeBs/e-nodeBs/eNodeB, eNB, and so forth.
Mobile telecommunications systems such as those arranged in
accordance with the 3GPP defined Long Term Evolution (LTE)
architecture use an orthogonal frequency division multiplex (OFDM)
based interface for the radio downlink (so-called OFDMA) and the
radio uplink (so-called SC-FDMA).
The base stations 101 of FIG. 1 may be realised as any type of
evolved Node B (eNodeB) such as a macro eNodeB and a small eNodeB.
The small eNodeB may be an eNodeB such as a pico eNodeB, a micro
eNodeB, and a home (femto) eNodeB that covers a cell smaller than a
macro cell. Instead, the base station 101 may be realized as any
other types of base stations such as a NodeB and a base transceiver
station (BTS). The base station 101 may include a main body (that
is also referred to as a base station apparatus) configured to
control radio communication, and one or more remote radio heads
(RRH) disposed in a different place from the main body. In
addition, various types of terminals, which will be described
below, may each operate as the base station 101 by temporarily or
semi-persistently executing a base station function.
Any of the communications devices 104 may be realized as a mobile
terminal such as a smartphone, a tablet personal computer (PC), a
notebook PC, a portable game terminal, a portable/dongle type
mobile router, and a digital camera, or an in-vehicle terminal such
as a car navigation apparatus. The communications device 104 may
also be realized as a terminal (that is also referred to as a
machine type communication (MTC) terminal) that performs
machine-to-machine (M2M) communication. Furthermore, the terminal
apparatus 104 may be a radio communication module (such as an
integrated circuit module including a single die) mounted on each
of the terminals
In the present disclosure, a base station providing a small cell is
generally differentiated from a conventional base station mostly
(and sometimes exclusively) in the range provided by the base
station. Small cells include for example the cells also called
femtocell, picocell or microcell. In other words, small cells can
be considered as similar to macrocells in the channels and features
provided to the terminals, but with the use of less power for base
station transmissions, which results in a smaller range. A small
can therefore be the cell or coverage provided by a small cell base
station. In other examples, the term small cell can also refer to a
component carrier when more than one component carriers are
available.
Moreover, mobile networks can also include Relay Nodes (RN) which
can further increase the complexity of the mobile system and of the
reduction of interference in a small cell network. Relay
technologies are known generally to provide an arrangement for
receiving signals from a base station and for retransmitting the
received signals to a UE in a mobile communications network, or to
receive signals transmitted from a UE for re-transmission to a base
station of a mobile communications network. The aim of such relay
nodes is to try to extend a radio coverage area provided by a
mobile communications network to reach communications devices which
would otherwise be out of range of the mobile communications
network or to improve the ratio of successful transmissions between
a terminal and a base station.
A mobile network which includes a variety of base stations and/or
relay nodes (e.g. macro-cell base stations, small cell base
stations and/or relays) is sometimes referred to as a heterogeneous
network.
Heterogeneous networks that would have very dense footprint of
access points will no longer be designed and set up in a
coordinated fashion by a single mobile network operator. Due to the
sheer number of small cells needed their installation will happen
much more in an ad hoc fashion, with end users and other non-MNO
entities also installing small cells. The overall network
management would still be done by an operator for all small cells
using that MNO's assigned frequency band. This evolution from
today's operator installed networks to more unplanned ad hoc
networks is what we refer to as `dense network` in this
description.
FIG. 2 illustrates an example heterogeneous system 200 for
communicating with at least a terminal 231. In this system 200, a
base station 201 provides a macrocell and six base stations 211-216
provide small cell coverage, potentially overlapping with the
coverage of the base station 201. Additionally, three RN 221-223
are provided and are operating with base stations 201, 214 and 212,
respectively. A relay node can generally be defined as a wireless
radio access point for relaying transmission and which thus does
not implement all of the functionalities of a base station. It is
in general not directly connected to the core network but uses
wireless access (inband or outband) for backhaul link to connect
with a base station. In other examples, the backhaul link may also
be provided over a wired connection. This is in contrast to a small
cell base station which, as mentioned above, can generally operate
like a base station and is thus connected to the core network, as
illustrated by the arrows between the small cell base stations
211-216 and the Serving Gateway "S-GW" in FIG. 2. Relay nodes may
also send or receive data with the terminals or base stations which
can also add to the complexity of dealing with interference in an
environment as illustrated in FIG. 2.
Another example of a heterogeneous environment is illustrated in
FIG. 3, where a macrocell base station 311 is provided in the same
area as small cells provided by a base station 301 in or in the
vicinity of a building, by a base station 302 in a first lamppost,
by a base station 303 in a second lamppost, by a base station 305
provided in a bus stop and by a mobile base station 306 provided in
a cyclist back-pack. In another example, the infrastructure unit
303 and 302 in lamp posts may be relay nodes relaying data in the
uplink and/or downlink to the macrocell base station 311 or to
another infrastructure unit (e.g. another relay node). In this
example, the interference and link quality experience can vary
greatly depending on traffic and on time: the cyclist may enter an
interference/poor link quality zone and later leave this are, while
the base station 301, if associated with an office, may potentially
only be used during office hours and may be turned off during the
rest of the day or the rest of the week. In such a heterogeneous
network, a terminal which is V2X-capable may wish to communicate
with any of the other nodes in the area depending on the
circumstances, such as whether the terminal is associated with a
vehicle and moving.
FIG. 4 illustrates an example route of a terminal associated with a
vehicle in a city environment comprising several road side units
(RSU). As can be seen in this example, the vehicle, and therefore
the terminal, may travel via several different routes and depending
on which route is chosen, different RSU may be best suited for
communicating with the terminal, in particular in a V2X
environment.
With a view to quickly identifying a suitable RSU a first step may
be to help differentiating RSU from other infrastructure units or
mobile nodes in the network. For example, if D2D protocols are used
for communications between terminals and RSUs, discovery signals
from RSUs may differ from discovery signals of other D2D nodes.
Example implementations include a new physical channel or signal
and/or an indicator in discovery signals that may be used for RSU
and/or V2X communications only and that can for example identify
discovery signal for RSUs. In an alternative or complementary
example, if V2X services are deployed on dedicated bands, all the
discovery signals on this band would be assumed as coming from RSUs
and/or other V2X nodes and no further differentiating may then be
needed (although it is not excluded). If however the RSUs share a
band with other types of nodes or communications (e.g. a legacy LTE
network) and/or with other potential D2D services, further
differentiation of discovery signals may be implemented (as
discussed above). While such an arrangement would improve the speed
at which RSUs can be detected and thus reduce the delay for the
terminal to connect with a relevant RSU, for example by then
prioritising connections with RSUs and/or V2X nodes over other
communications or connections, with a view to further reducing
delay, it can be attempted to identify a suitable for the terminal
with a view to reducing delay compared to other RSUs or to keeping
delay at an acceptable level.
This can however prove challenging in a V2X environment which
involves both low-delay communications and moving terminals,
potentially at high speeds. For example in FIG. 4, when the
terminal is in the centre of the intersection served by RSU9, it
likely may find and measure both RSU 8 and RSU 6, potentially with
similarly good links. In a conventional mobile telecommunication
arrangement and in the absence of any other information, the
deciding factor for selecting the RSU to connect to would be based
on the quality of the links between the terminal and the RSUs, for
example on the respective received power from the two RSUs. An
example of such a conventional decision process--applied to
changing serving RSU--is illustrated in FIG. 5. The process
generally follows four steps: (1) the UE identifies the target RSU,
for example when a discovery signal is received from the RSU and/or
when its received power becomes greater than a threshold; (2) a
reporting event is detected, for example the received power of the
target RSU exceeds that of the current RSU by more than a
threshold; (3) as a result the terminal sends a measurement report
to a relevant base station and (4) the base station effectively
transfers the terminal to the target RSU by allocating resources
for the terminal to communicate with the target RSU instead of the
serving RSU. Returning to the example of FIG. 4 when the vehicle is
served by RSU9, there are four likely outcomes once the terminal
has reached the intersection and can detect both RSU6 and RSU8: RSU
6 is measured as stronger and selected, and the vehicle turns right
RSU 6 is measured as stronger and selected, and the vehicle
continues straight ahead RSU 8 is measured as stronger and
selected, and the vehicle turns right RSU 8 is measured as stronger
and selected and the vehicle continues straight ahead
Two out of the four cases above will select the most appropriate
RSU with a view to trying to reduce delay in communications, in
particular for a V2X-enabled terminal. However, in two remaining
cases, the RSU selection is likely to cause delay in the
distribution of information regarding the relevant intersection to
the terminal as the terminal will then have to detect that the
newly-selected RSU was not the most appropriate one and re-select
the other RSU, thereby introducing delay, before it can communicate
with the RSU actually located at the intersection the vehicle is
using. In other words, the conventional decision process used in
mobile telecommunication systems and applied to RSUs will, in a
significant number of cases (possibly more than 50% if more than
two routes are available to the vehicle), result in a sub-optimal
selection of RSU which will cause delays. Such delays are highly
unlikely to be found acceptable in a V2X environment where
low-delay and high-reliability transmissions may be required and
reducing these delays would thus improve the compliance with V2X
and other low-delay environments.
In effect, when a V2X enabled UE traverses across a grid of RSUs,
considering only the nearest/strongest RSU (in a conventional
manner as discussed above) is unlikely to be found acceptable on
its own. On the other hand, identifying a "relevant" RSU would
improve delay reduction but can be challenging as a large number of
factors can impact which RSUs may be considered as relevant or not
relevant. Measurements may provide one tool with a view to
facilitating the selecting a RSU which is relevant or relevant
enough for a terminal, e.g. a V2X-enabled terminal. For example,
based on measurements, a list of RSUs which are of good enough link
quality to connect to may be determined (e.g. by a base station)
and, from this list of "connectable" RSUs, it may be determined
(e.g. by the base station) which RSU or RSUs are located in an
expected direction of travel for the terminal, communication
resources may be assigned accordingly for the terminal to
communicate with the RSU (or RSUs).
FIG. 6 illustrates an example method of allocating resources.
First, as step S601, measurements relating to links between a
terminal and infrastructure nodes are obtained. For example, if the
method is used in a V2X environment, the infrastructure nodes may
be RSUs communicating with a terminal in a vehicle. The
measurements may be any one or more suitable types of measurements
which may be indicative of a received power in a band (e.g. RSSI or
RSSI-like measurement), a received power from a node (e.g. RSRP or
RSRP-like measurement), a signal-to-noise ratio or likewise (e.g. a
RSRQ or RSRQ-like measurement) a link quality (e.g. CQI or CQI-like
measurement) or any other measurement indicative of a power and/or
quality of a link. Also, a measurement may be for carried out
across an entire band to be used for communications, or across a
larger or smaller band and, in some cases, it may additionally be
normalised to a specific bandwidth, for example the bandwidth of a
single sub-carrier in an LTE environment.
At step S602, direction information is obtained for the first
terminal. The direction information may be obtained independently
from the measurements, for example from a geo-localisation module
associated with the terminal and/or vehicle. In this case, the
method may also rely on a map associating the infrastructure nodes
with a corresponding geo-localisation position which can assist in
determining whether the direction of the terminal is towards or
away from infrastructure nodes. Alternatively or additionally, the
direction information may be obtained from the measurements. In
some examples, direction information may be obtained at least in
part from two or more measurement made at different times but for
the same link. If the strength of the signal received from an
infrastructure unit increases from a first point in time to a
second point in time, it may be assumed or inferred that the
vehicle/terminal is moving towards the infrastructure unit.
Likewise, if the strength decreases, it may be assumed or inferred
that the vehicle/terminal is moving away from the infrastructure
unit.
At step S603, a candidate infrastructure node for the terminal may
be determined based the measurements and direction information. A
variety of conditions may be used when determining whether an
infrastructure node may be a suitable candidate node. For example,
one or more minimum thresholds may be required for the measurements
and, from nodes meeting these one or more thresholds, candidates
nodes may be those closest to the expected direction of travel of
the terminal which can be derived from the direction information.
For example, if a terminal moves away from an infrastructure node
or does not move towards the infrastructure node enough (e.g. if it
is considered that the terminal is more likely to be moving
alongside the node rather than towards it, even if such movement
may involve a period of getting closer to the node), this node may
not be considered as a candidate node. On the other hand if a
terminal moves towards an infrastructure node (either at all, or to
a degree considered as sufficient), this node may then be
considered as a suitable candidate node. In the example of FIG. 4,
once the terminal has turned right at the intersection for RSU9, it
may be found that RSU8 and RSU6 may each meet the measurements
requirements but also that the terminal is not moving towards RSU8
but is moving towards RSU6. As a result, RSU6 can be selected as a
candidate infrastructure node. In other words, based on the
measurements and direction information, it is expected to be a
suitable infrastructure node for the terminal to communicate with
when trying to reduce communication delays caused by a poor RSU
selection.
At S604, resources for the terminal to communicate with the
candidate infrastructure node are allocated. The resources can be
allocated in any suitable manner, thereby effectively allowing the
terminal to communicate with the candidate infrastructure node. In
the example of FIG. 6 or in other examples, the resource allocation
may be communicated to the infrastructure node and/or terminal. In
one example, the resource allocation information is transmitted to
the infrastructure node which can then allocate the resources for
the terminal and inform the terminal of the resources that have
been allocated to it, for example in a part of the signals it is
transmitted which can be used for signalling resource allocations
to terminals or other nodes. In another example, both the
infrastructure node and the terminal receive, from a base station
for example, an indication of the resources allocated for them to
communicate and they may then both use the resources as soon as
technically possible to communicate with each other. Whichever
technique is chosen for informing the terminal and infrastructure
node of the resources that have been allocated, the two entities
can then communicate and, in view of the candidate infrastructure
node having been selected based on the direction information, the
communications are less likely to suffer from delay resulting from
an unsuitable node selection.
Also, in some examples, if resources were previously allocated for
the terminal to communicate with another infrastructure node and if
it is considered that these resources are no longer required, they
can then be de-allocated. Like for the allocation of resources, the
de-allocation of resources can be signalled to the terminal and/or
the other infrastructure node as deemed appropriate. Whether
resources need to be de-allocated can also be determined based on
direction information and measurements and, in some cases, it may
further be based on whether a candidate infrastructure node has
been identified at S604. In one example, de-allocation of resources
may be based on at least one of: measurements falling below one or
more thresholds and the direction of the terminal being considered
as being away from the infrastructure node (or as not being towards
the infrastructure node). In another example, a terminal may only
be communicating with one node and as soon as resources are
allocated to an newly identified candidate infrastructure node, any
resources previously allocated for communicating with another node
may then automatically be de-allocated. In yet a further example, a
combination of these may be implemented, with for example a
terminal being allowed to communicate with up to N nodes (with
N.gtoreq.2) and, any time a new candidate is identified, it can be
determined which nodes of the previous selection of infrastructure
nodes may be kept or removed based on measurements and direction
information. In other words, the de-allocation of resources may be
based on the measurements and/or direction information for the
terminal, and optionally, on any further suitable criteria.
While in the previous example it has generally be assumed that
measurements are carried out for a single link between a terminal
and a base station, in other examples, measurements may be carried
out fora plurality of links between the terminal and the base
station, if for example the base station includes one, two or more
Remote Radio Heads (RRH) or any other types of additional radio
antenna. FIG. 7 illustrates an example RSU having a plurality of
remote radio heads (RRH). In this example, RSU5 is provided with
four RRH, namely RRH 5-1, 5-2, 5-3 and 5-4, one for each of the
branches of the intersection. Accordingly, the granularity of the
measurements can be improved and more accurate direction
information may be derived from measurements, in cases where it is
at least in part derived from measurements. For example, in the
event that direction information is derived from measurement
information, the measurements with each of the base station and the
RRH can potentially be used to try to obtain accurate direction
information. For example, if it is detected that the power received
from RRH 5-2 is strong but decreases while the power for RRH 5-1,
5-3 and 5-4 is less strong but increases, it may be assumed that
the vehicle is in leading to the intersection for RSU5, along any
of the three arrows of FIG. 7. Then, the vehicle can still go in
three different directions (ignoring a U-turn direction for the
sake of simplification only) and the measurements from the RRH for
RSU 5 can further help with estimating the direction of the
vehicle: if it is detected that power received for RRH 5-1
increases, that power received for RRH 5-3 decreases, while power
received for RRH 5-2 and 5-4 decrease in a similar manner, it may
be assumed that the vehicle is going in the direction of the plain
arrow; if it is detected that power received for RRH 5-4 increases,
that power received for RRH 5-2 decreases, while power received for
RRH 5-1 and 5-3 decrease in a similar manner, it may be assumed
that the vehicle is going in the direction of the dashed arrow; and
if it is detected that power received for RRH 5-3 increases, that
power received for RRH 5-31 decreases, while power received for RRH
5-2 and 5-4 decrease in a similar manner, it may be assumed that
the vehicle is going in the direction of the dotted arrow.
This information can be used in addition with measurements from
other base station and/or RRH, if available, with a view to improve
the accuracy of the direction information that can be derived from
the measurement information.
The terminal may have two or more radio modules and may be able to
use each independently to make measurements with the base station
(with or without any RRH or equivalent). In some cases, if the
position of the additional radio modules are known with respect to
the vehicle's orientation (e.g. at a front or back position),
direction information may already be derived from measurements made
by the plurality of radio modules, with the measurement being
carried out at substantially the same time, rather than subsequent
measurements. While subsequent measurements may also be used, for
example with a view to further improving the accuracy of the
direction information, direction information may in this case be
obtained from the substantially simultaneous measurements using two
or more radio modules of the terminal which are spaced from each
other. This may also be used in combination with making measurement
for a base station provided with one or more RRH.
The direction information may be obtained using different
techniques and, when it is at least in part derived from
measurements, the direction information may be obtained by the
terminal, infrastructure node (e.g. a road side unit in a V2X
environment), a base station, or any other suitable element which
may then have access to the measurements. While each of these nodes
is suitable for deriving direction information from measurements,
the base station or another element connected to the base station
may in some example be used as these elements are likely to have
higher computing capabilities compared to terminals or
infrastructure unit and may therefore be able to carry out more
complex calculations which in turn may improve the accuracy of the
direction information. In other cases, it be found that it is
preferable to estimate at least a first estimation of the direction
information at the terminal or infrastructure node level such that
the selection of where to carry out such a step can be decided
based on specific considerations for each individual
arrangement.
When deriving direction information from measurements, the
direction information may be derived based at least in part on, or
using, a representation of the infrastructure nodes and of the
connections between them, for example roads between intersections
in the event that the infrastructure nodes are associated with an
intersection. An example representation is a graph which can have
infrastructure nodes as vertices and roads connecting the
infrastructure nodes' locations as edges which can for example be
unidirectional (e.g. one way roads) or bidirectional. FIG. 8
illustrates an example graph representing a RSU network and routes
between the RSUs for an arrangement similar to that of FIG. 4. A
vehicle or pedestrian in such an environment may follow routes
which are represented by the edges. The use of such a mapping of
the infrastructure nodes against a real-life environment
illustrating the possible routes or paths for a vehicle can be
useful for estimating the direction information from the
measurements. If for example the changes in the measurements
correspond to a pattern of change that would be expected if a
vehicle follow the path RSU7-RSU8-RSU5, then it is likely that this
is the path that the vehicle is following.
While the graph of FIG. 8 illustrates a somewhat simplified
environment, FIG. 9 illustrates another example graph representing
a RSU network and routes between the RSUs which has a more complex
structure than that of FIG. 8. For example, not all RSUs may be
connected with a (geographically) neighbouring one, there may be
unidirectional edges between two vertices, more than one edge can
be provided between two vertices, an edge connecting two vertices
but going very close to a further vertex it is not connected to,
etc. Although FIG. 9 does not exhaustively cover all possible types
of variations for graphs, it is useful in understanding that, by
using a mapping technique for the infrastructure nodes and possible
paths for the terminals, direction information may be obtained more
accurately as it can effectively reduce the number of possible
position and direction for the terminal from potentially "anywhere"
and "any direction" to "on or near an path" (edge/vertex) and
"along an edge". By reducing the number of possible positions
and/or directions from which the expected direction of travel of
the terminal can be derived, there can be achieved a significant
reduction in the amount of processing required and a significant
improvement in the accuracy of the direction information thereby
obtained.
Additionally, direction information derived from measurements may
be cross correlated with direction information obtained in any
other way, for example using any of: a geolocation module
associated with the terminal, using a detection signal from a fixed
detector placed on a side of a road which can report which terminal
is can detect in its vicinity, etc. Likewise, in some examples,
direction information not derived from measurements is the primary
source of direction information and it can in some instances also
be cross-correlated (temporarily or permanently) with direction
information obtained from measurements.
FIG. 10 illustrates another example method of allocating resources.
In this example, a base station receives measurements from at least
one terminal and also allocates the resources for the terminal to
communicate with a candidate infrastructure node, wherein the
terminal and infrastructure nodes are V2X-enabled and communicate
using D2D or D2D-like communications. As the skilled person will
understand, the teachings provided in respect of FIG. 10 and its
discussion can also be applied to other type of environments or
arrangements, in accordance with the present disclosure. At S1001,
the base station receives one or more measurement reports from a
terminal. Based on this, the base station determined at S1002
whether there is more than one RSU with a strong enough
measurement. This may involve for example determining whether a
power is above a threshold and/or a link quality meets a minimum
requirements and/or any other criterion is met for each RSU in the
measurements. In the event that no RSU can be detected with a
strong enough signal, on the basis of the measurements, the can
stop (and in some example it can also de-allocate any resources
previously allocated to the terminal. If only one RSU is detected
with a strong enough signal, the method can move on to S1003 where
D2D resources are allocated to the terminal and identified RSU, for
them to communicate, and the method can then end. In this case,
relying on direction information may not be efficient as it is
unlikely to have any effect on the resource allocation as the
terminal would not be likely to be able to communicate with any
other RSU.
On the other hand, if two or more RSUs are detected with a strong
enough signal, it may then become more important to select the RSU
which is likely to reduce delay the most and direction information
may then be used to assist with this selection. In the example of
FIG. 10, the base station considers each of the RSUs in turn
(S1004). For each relevant RSU, the base station can take into
account the terminal direction information (S1005) that has been
received from the RSUs in this example, to determine whether the
terminal is moving towards the RSU or not (S1006). If the terminal
is not moving towards the RSU, the method considers the next RSU,
if any, (S1008) and returns to S1004 previously discussed. If
however the terminal is moving towards the RSU, the base station
can then assign D2D resources for the terminal and this candidate
RSU to communicate (S1007), the resources being for example
selected from the pool of D2D resources for this RSU. The method
can then end. As a result, the terminal is only allocated resources
to candidate RSU which are more likely to be the most or one of the
most relevant RSUs for this terminal, thereby improving with the
delay reduction.
Alternative RSU or infrastructure node selection may also be
carried out. For example, in another arrangement, a score can be
calculated for each RSU based on an indication of how much the
terminal moves towards the RSU. For example, a terminal moving in
the opposite direction from the RSU may be given a score of 0 and
may be given 1 if moving directly towards the RSU for scores
varying from 0-1 (e.g. in a linear or non-linear manner). In other
examples, the same situations may attract scores of -1 and 1,
respectively, while moving in a direction substantially
perpendicular to these two directions would attract a score of 0.
Then, the RSU with the highest score may be selected as probably
the most relevant one and resources may be allocated for the
terminal to communicate with this terminal. The scores based on
direction information may also be weighted based on any relevant
weight, for example based on the measurements (with closer
infrastructure nodes being give a weight which increases the
likelihood of the node being selected) and/or on whether the RSU
already has resources allocated for communications with the
terminal (e.g. to avoid an early disconnection from a current RSU
in some cases) to generate the final score upon which the selection
of the candidate infrastructure node can be made.
FIG. 11 illustrates an example method of a terminal reporting
measurement information, or sending measurements reports, which may
be used for selecting one or more candidate infrastructure nodes
for allocating resources for the terminal. First, at S1101, the
method is initialised and at S1102 the terminal detects a discovery
signal from an infrastructure node (or RSU in this case) and if a
discovery signal is detected, one or more measurements are carried
out S1103 for this newly detected RSU. Then the terminal determines
if any further infrastructure node can be detected at S1104. If
another node can be detected, the terminal increases its counter
(S1105) and returns to S1105. On the other hand, if no further
infrastructure node can be detected or discovered, the terminal
sends a measurement report to the base station. The measurement
report can include one or more measurements for each of the
infrastructure node that has been detected. While in this example
the measurement report is sent once all infrastructure nodes have
been detected and measured, in other examples the terminal may send
a measurement report once N nodes have been detected and measured
(N.gtoreq.1) and/or once a timer T has expired so that the report
can be sent once they have reached a certain size and/or if no
report has been sent for a time period T.
In the example of FIG. 11, the terminal detects and measures a
indicator of a link between the terminal and the infrastructure
node (and/or between any additional radio unit of the base station
such as an RRH). Alternatively or additionally, an infrastructure
node may make measurement with on one or more terminals and report
the measurements to the base station. In the case the base station
includes one or more additional radio units, such as RRHs, the
measurements may be for links between the terminal and any of the
base station and the radio units.
FIG. 12 illustrates another example method of a terminal reporting
measurement information. In this example, relative measurement
information is derived at the terminal and reported to the base
station. The base station (or the relevant element) may make use of
the relative measurement information to obtain direction
information and thus to select one or more candidate infrastructure
node for allocated resources for communicating with the terminal.
First, at S1201 measurements are made for links between the
terminal and one or more infrastructure nodes. Then, from
successive measurements, relative measurement information
indicative of an evolution in time of measurements for the measured
links may be derived (S1202). For example, the terminal may compare
a measured signal strength at a time T and at a later time T+t and
identify that the signal strength has essentially increased,
decreased or remained the same. The relative measurement
information may in some case an qualitative indication of the
evolution of the measurement (e.g. up, down or stable) while in
other cases it may be a quantitative indication, such as numerical
value indicating the amount of change, positive or negative,
between the compared measurements. Finally, at S1203, the terminal
may report the relative measurement information to the base station
and/or infrastructure nodes. While the terminal may report relative
measurements information only, in other cases the measurement
information reported by the terminal may further comprise direct
measurement information, for example measurement information
directly based or comprising the measurements made for the
links.
Accordingly, with a view to reducing delays in communications, one
or more candidate infrastructure nodes may be selected for
communicating with a terminal wherein, by using direction
information for the terminal for the selection, it is expected that
only relevant nodes will be selected for communicating with
terminals, thereby reducing delay caused by a poor infrastructure
node selection process.
Once it is has been decided which infrastructure nodes will
communicate with which terminal, which may sometimes be referred to
as a terminal (or terminals)-infrastructure node (or nodes)
association in the interest of conciseness, the resources can be
allocated to the terminals and infrastructure nodes
accordingly.
Conventionally, the base station is in charge of D2D resource
allocation. The base station is unaware of whether a terminal
intends to use resources to communicate and therefore allocate
resources upon receiving a request from the terminal. In one
example, Rel'12 MAC specifications state that in order to transmit
on the SL-SCH (SideLink Shared Channel) the MAC entity must have a
sidelink grant. The term "sidelink" generally refers to direct
communications from a D2D device to another D2D device (while
uplink and downlink refer to communication with a base station in
the conventional sense). The sidelink grant is selected as follows
[2]: if the MAC entity in the terminal is configured to receive a
sidelink grant dynamically on the PDCCH or EPDCCH and more data is
available in STCH than can be transmitted in the current SA period,
the MAC entity shall using the received sidelink grant determine
the set of subframes in which transmission of Sidelink Control
Information and transmission of first transport block occur. The
transmission under this sidelink grant may occur in subframes
starting at the beginning of the first available SA Period which
starts at least 4 subframes after the subframe in which the
sidelink grant was received The configured sidelink grant is always
cleared at the end of the corresponding SA Period.
Accordingly, the terminal must request a new sidelink grant
whenever it has data to send on the SL-SCH. In D2D, this mode of
resource allocation is called "Mode 1". Accordingly, the use of
resources may be optimised as the base station can avoid collision
between simultaneous transmissions and even use frequency planning
to reduce the risk of interferences while increasing the use of
frequency resources. FIG. 14 illustrates an example of conventional
D2D Sidelink resources assignment period (SA). In this example, in
a first SA (Scheduling Assignment) period, using resources
available for sending scheduling assignments (e.g. on a physical
sidelink shared channel "PSSCH"), the terminals indicate on the
saSubframeBitmap which resources they use for transmission during
the T-RPT occasions. The resources indicated and used by a terminal
are those that were granted to it in response to a previous request
for resources from the terminal. At the end of the SA period, the
sidelink resource grant is cleared and the terminal must request a
new grant if it has more data to be transmitted. It is noteworthy
that in the latest MAC specification TS36.321 V12.5.0 [2] the SA
period is referred to as SC (Sidelink Control) Period.
According to the 3GPP specification therefore the following
terminology is used to describe a currently proposed arrangement
for D2D communications: Scheduling Control (SC) are physical layer
control messages providing an indication to communication resources
on a physical sidelink shared channel (PSSCH), which may be more
generally referred to as a shared channel. The SC messages are
transmitted on a Physical Scheduling Control Channel (PSCCH). The
Physical Scheduling Control Channel (PSCCH), which may be more
generally referred to as a scheduling channel, is used to transmit
control information, which is referred to as Sidelink Control
Information (SCI). The transport channel mapped to the PSSCH is the
Sidelink Shared Channel (SL-SCH) and the logical channel mapped to
the SL-SCH ist he Sidelink Traffic Channel (STCH) SCI may be used
not only for scheduling but also for other control information like
Timing Advance. Alternatively, 3GPP specifications also describe a
second mode of resource selection wherein the terminal selects
resources from a D2D resource pool when they wish to transmit
something. In this case the resources are randomly selected from a
pool of resources configured by higher layers. This mode is called
"Mode 2". While resources may be used straight away by the
terminal, without any prior request and scheduling assignment
exchange, there is also a risk of collision with transmissions from
another terminal in view of the lack of any prior planning on which
terminal (or other D2D node) will be using which resources. As a
result, due to the risk of collisions, the risk of retransmissions
is significantly higher compared to a mode 1 or convention mode for
resource allocation and a resource allocation in a D2D-Mode 2 or
the like is not suitable in environments where a low latency is
required, e.g. in a V2X environment. Therefore, in this type of
environments, a Mode 1 or Mode 1-like type of resource allocation
has generally been preferred. However, in some examples (such as in
a D2D example), the cycle for allocating resource may be of 40 ms
or more which, as discussed above, could result in a transmission
needing potentially up to 80 ms (or more if the cycle is more than
40 ms) before it can be fully transmitted. This may not be
acceptable in some low-delay environment. Resource Allocation
Techniques
In our co-pending European patent application number 15174399.4
there is proposed an improved technique to allocate communications
resources, in a semi-persistent fashion, in which resources are
allocated for a terminal for a duration longer than a single
Scheduling Assignment (SA) Period, which in 3GPP terminology is the
scheduling control (SC) period. Semi-persistent allocation of
resources means that the terminal has access to the resources
across multiple SC periods (in some examples the same resources
across the multiple allocation periods) without explicitly having
to request and be assigned further resources. Until the resources
are released, it is expected that one unique terminal is
communicating across those resources with an infrastructure unit.
The initiation of semi-persistent allocation may begin with a
terminal requesting resources, or it may be initiated by the base
station assigning resources to a terminal when it is considered
that the terminal has to communicate with an infrastructure unit
(i.e. in a spontaneous manner in the absence of a resource
allocation request from the terminal). Due to latency
considerations, the resource assignment and release may be
signalled via physical layer control channels, but RRC signalling
or any other suitable type of signalling may also be used.
Accordingly, due to the reduced need for the terminal to request
further resources before it can communicate over two or more
allocation periods, the delay for the terminal to be able to
communication, and thus the delay in the transmissions between the
terminal and the infrastructure node can be reduced.
FIG. 13 illustrates an example of allocating resources to a
terminal in the absence of a resource allocation request. First, at
S1301, measurements are obtained, wherein the measurements relate
to links between a terminal and infrastructure nodes. As previously
mentioned, in cases where there could be one or a plurality of
links between a terminal and an infrastructure node--for example
depending on whether the terminal and/or infrastructure node
comprises one or more additional radio elements (e.g. RRH). At
S1302 the communications between the terminal and the
infrastructure nodes are identified as delay-sensitive
communications. This can be based for example on any of: the base
station having a table of indicators of which terminals,
infrastructure nodes and/or combinations thereof are expected to
carry out delay-sensitive communications; on an indicator included
in a resources allocation request (if used) from the terminal; on a
look-up from a database of indicators for terminals, infrastructure
nodes and/or combinations thereof; on any other suitable methods or
means; or on any combination thereof.
The method then moves to step S1303 where resources to allocate for
the terminal to communicate with the infrastructure node(s) are
identified based on the measurements and on the previous
identification of delay-sensitive communications to be carried out.
Based on the resources identification, said resources can be
allocated for the terminal to communicate with the infrastructure
node(s) at S1304. For example, based on measurements, it can be
determined (e.g. by a base station or other element) that the
terminal is in the vicinity of an infrastructure node (e.g. a RSU)
and is therefore likely to wish to communicate with it with
delay-sensitive communications, for example for vehicle safety
purposes. Rather than wait for a resource assignment request to
allocate resources individually for each relevant period in turn,
the resources can be allocated for two or more period so that they
are already available in case they are needed by the terminal in
the future. Accordingly, the delay for the terminal to communicate
with one or more infrastructure nodes over two or more allocation
periods can thereby be reduced as resources are pre-allocated for
the terminal for this plurality of periods, before it is known
whether they will be needed or not. While this goes against the
conventions in mobile networks and is likely to reduce the
efficiency of the network (in terms of resource usage), this can
also reduce delays in the transmissions as the sidelink resources
can be used by terminals very quickly within these periods (as the
resources are already available to the terminal as soon as they are
needed, if they are needed) whilst also avoiding the risk of
collisions with transmissions from other terminals or nodes.
Semi-persistent allocation of resources furthermore provides a
terminal much faster access to the Physical Sidelink Shared
Channel. For example, while D2D transmissions based on existing
Mode 1 or Mode 2 may have an SA cycle of 40 ms or more, a terminal
may access the semi-persistently assigned resources at any T-RPT
instance. Accordingly, the delay from the terminal wishing to
transmit data and actually transmitting data over this longer
period can be significantly reduced. In some examples, as soon as
the terminal is in the vicinity of an infrastructure nodes,
resources can be allocated to the terminal in the absence of a
resource allocation request from the terminal. In this case, rather
than having to send a request and wait for the assignment in
return, the terminal will receive an assignment straightaway,
thereby further reducing the delay for the terminal to be able to
communicate compared to a conventional resource allocation
arrangement.
FIG. 14 illustrates an example comparison of a D2D resources
allocation with a resource allocation in accordance with the
present disclosure. In FIG. 14 a plain arrow 1401 illustrates when
the resources for a conventional D2D terminal will be allocated
(the scheduling assignment being only received after the terminal
has successfully transmitted a resources allocation request to the
base station--see the double-lined arrow 1402) whereas a dotted
arrow 1404 illustrate when the terminal can access a transmission
resource provided by the semi-persistent scheduling assignment in
accordance with the present disclosure. Accordingly, the delay for
the terminal to be in a position to start communicating with the
one or more infrastructure nodes (for receiving and/or sending
transmissions) can be significantly reduced and the resulting
arrangement is thus more likely to be suitable for low-delay
environments, such as V2X environments.
An alternative view of a mode two operation in which resources are
allocated to a terminal in accordance with a conventional D2D
operation is showing in FIG. 15. In FIG. 15, resources are
allocated to a terminal by one of the terminals transmitting a
resource allocation message in the scheduling control (SC) 1501
which allocate resources in the shared channel 1502 as explained
above in accordance with currently proposed 3GPP terminology. The
allocations within the shared channel 1501 provide identifying
indications such as pointers 1504, 1506, 1508 to the shared channel
resources 1510, 1512, 1514, 1516 as well as examples in a
subsequent frame 1518, 1520, 1522, 1524. Thus a terminal receiving
a message according to a bit frame map from the SC 1501 can
identify its resource allocation from an identifier that terminal
device recognises and receives a pointer 1504, 1506, 1508 which
directs the terminal to the communications resources 1510, 1512,
1514, 1516 within the shared channel 1502. The bit map of the SC
1527 is comprised of different sections 1528, 1530 which identify
physical resource blocks and provides a PUCCH transmission to the
terminal devices.
FIG. 16 illustrates an example method of allocating resources at an
infrastructure unit, which can be carried out with an allocation
request from the terminal or in the absence of a resource
allocation request from the terminal. At S1601, the infrastructure
node receives an allocation message for allocating resources for
the infrastructure node to communicate with the terminal, wherein
the resources are for two or more allocation periods. Based on the
allocation message, the infrastructure node can then access the
allocated resources to communicate with the terminal during the two
or more allocation periods (S1602). The infrastructure node can
accordingly communicate with the terminal using the resources
identified in the allocation message (e.g. a scheduling assignment)
without the terminal having to request the resources for each of
the allocation period. In some examples the terminal will receive
an indication of the allocated resources, for example from the base
station and/or from the infrastructure node, such that each of the
terminal and infrastructure node are aware of which resources to
use for sending signals and which resources to listen to for
receiving signals. Accordingly, resources can be allocated at an
infrastructure node to communicate with a terminal in a manner
which reduces delays in the transmissions between the
infrastructure node and terminal.
In some examples, the method may also comprise obtaining
measurements relating to a link between the terminal and the
infrastructure node. In this example the measurements can be
obtained either by the infrastructure node making its own
measurements and/or by receiving measurements from a terminal. The
measurements are then transmitted to the base station for
allocating resources.
FIG. 17 illustrates an example method of communicating between a
terminal and one or more infrastructure nodes which can be carried
out with an allocation request from the terminal or in the absence
of resource allocation request from the terminal. The terminal
receives at S1701 an allocation message indicating resources
allocated for the infrastructure node(s) to communicate with the
terminal, the allocated resources including resources from two or
more allocation time periods. As discussed above, the allocation
message may be received in any suitable form. In some examples it
will receive from the base station and/or infrastructure node. It
may also be received via a dedicated channel and/or dedicated
timeslots within a channel or frequency band. The terminal is then
able to communicate with the infrastructure node(s) during the two
or more allocation time periods using the resources indicated in
the allocation message (S1702). Accordingly, the delay for the
terminal to be able to communicate with the infrastructure node for
a plurality of allocation periods can thereby be reduced.
In some examples, the method may also comprise the terminal
obtaining measurements relating to a link between the terminal and
one or more infrastructure nodes and, then, the terminal
transmitting the measurements to the base station and/or the
infrastructure node(s) for allocating resources.
Accordingly, there has been provided an arrangement where the
allocation of the resources has been sped up thereby reducing delay
in transmissions which can be used with a view to improving a
compliance with a low latency system (e.g. a V2X system). While the
resources allocation delay can thereby be reduced, the resources
are still used in an "allocated" mode (which differs for example
from a D2D-mode 2 allocation mode) and the resource utilisation can
thus be controlled. While resources may be allocated that will not
be needed by the terminal (thereby reducing the utilisation
efficiency for the network), the resources can still be allocated
such that the same resources are allocated to different
terminal(s)/infrastructure node(s) associations which are in
different areas. For example, FIG. 18 illustrates an example
network with three RSUs and resources allocated to each RSU for
communications with the terminals. In this example, as the RUS1 and
RUS3 are remote from each other, depending on their range, they may
be allocated resources from the same resource pool. In other words,
there may be a partial or complete overlap in frequency and/or time
between the sidelink pool 1 and the sidelink pool 3 wherein the
resources can be allocated base the eNB (base station). On the
other hand, at there is a (geographical) overlap between the
transmissions from RUS1 and RUS2 and between the transmissions from
RUS2 and RUS3, overlap (in frequency and/or time) in resources from
sidelink pools 1 and 2 and sidelink pools 2 and 3 may be avoided
and reduced with a view to reducing interferences or collisions.
Accordingly, it can be attempted to compensate, at least in part,
for some of the reduced efficiency in resource utilisation that
result from the spontaneous resource allocation of the present
disclosure by improving the selection of resources allocated for
the infrastructure nodes with a view to increase re-use of the same
resources while avoiding collisions.
Improved Resource Allocation Technique
Embodiments of the present technique can provide an improved
arrangement for allocating resources to terminal devices which is
effective within a device to device type communications
environment. In particular, one of the terminal devices may act as
a roadside unit (RSU) and request resources from an eNB on which to
perform data communications, which follow the same pattern of
communications resources requiring for example low latency and a
relatively small amount of data. In a first example the resource is
allocated as an autonomous resource allocation mode and in second
example the resource is allocated in a schedule resource allocation
mode. Currently proposed arrangements for resource allocation do
not meet a requirement for vehicle safety, which is, in particular
to satisfy latency requirements for vehicular safety (collision
avoidance) which require an end-to-end latency of 100 ms as a
maximum in European, US and Japanese standards. As indicated above,
the options for resource allocation includes either scheduled
resource allocation from an eNB to a UE or UE autonomous resource
selection. Scheduled resource allocation can be characterized by:
The UE needs to be RRC_CONNECTED in order to transmit data; The UE
requests transmission resources from the eNB. The eNB schedules
transmission resources for transmission of Sidelink Control and
data; The UE sends a scheduling request to the eNB, either by D-SR
or by transmitting a Random Access message followed by transmitting
a proximity-based services buffer status report message. Based on
the proximity services buffer status report, the eNB can determine
that the UE has data for a proximity based services Direct
Communication transmission and estimate the resources needed for
transmission. The. eNB can then schedule transmission resources for
the proximity-based services Direct Communication using a
configured SL-RNTI.
In contrast, UE autonomous resource selection is characterized by
the UE being arranged autonomously to select resources from
resource pools and in which to transmit Sidelink Control and data.
FIG. 15 provides an example of UE autonomous resource selection
from resources, which are available for D2D communications.
According to previously proposed 3GPP systems (currently LTE
Release 12 specifications) key parameters impacting communications
latency are discovery resource pool period lengths and
communications resource pool period lengths. Specifications for
radio resource connection (RRC) set discovery resource pool periods
of lengths from 32 subframes up to 1024 subframes, and
communications resource periods from 40 subframes up to 320
subframes (for FDD). However, considering that one subframe is 1 ms
in duration and the communication may necessitate retransmissions,
reaching 100 ms is not possible with current D2D settings. In
addition, an RSU is intended to serve multiple vehicles. As such,
in contrast to previously proposed D2D communication techniques,
which are expected to serve only one or two groups (broadcasting
same session) the RSU needs to be able to schedule several groups
of vehicles. This implies additional overhead especially in case of
scheduled resources by the eNB.
A semi-persistent resource scheduling technique for D2D
communications resources, which is explained above and disclosed in
our co-pending European patent application number 15174399.4.
However this is also a need for signaling and allocating
semi-persistent communications resources. There is also a
requirement for UEs to receive scheduled resources to ensure that
the resources have been scheduled for a UE to receive the scheduled
resources before a transmitting terminal transmits on the
resources.
Embodiments of the present technique can provide an arrangement in
which multiple semi-persistent resource patterns are configured,
for example by an eNB using a broadcast signalling, or the multiple
semi-persistent resources are pre-defined or pre-configured. The
semi-persistent resource patterns can be used for both autonomous
resource allocation or scheduled resource allocation:
For the example of the autonomous resource allocation mode, an RSU
or UE can reserve resources semi-persistently, following the
patterns provided. This becomes semi-autonomous mode because a pool
of resources are scheduled by an eNB on a semi-persistent basis,
but then the RSU can select which of the assigned resources to
allocate and to communicate with different UEs. This can also be
interpreted as a dynamic resource pool allocation. This is because
in some embodiments an eNB can provide an indication identifying
one of a number of pre-defined resource pools in response to
scheduling request from the RSU, which indicates for example the
number of UEs served or the total amount of data that needs to be
scheduled. This would not be group specific but rather the overall
amount of data.
For the example of the scheduled resource allocation mode, an eNB
can schedule one of the resource patterns according to a
conventional arrangement, instead of providing an indication
identifying one resource set per SC-period. It will be appreciated
from the explanation above that the SC-period is a time duration
for which resources have been scheduled for a UE. According to one
example, the UE requests and is granted resources using an
indication identifying a pattern of resources according to the
procedure below:
Step 1: D2D UE sends buffer status report (BSR) to eNodeB
Step 2: D2D UE sends the Dedicated Scheduling Request (D-SR)
Step 3: eNodeB schedules The D2D resources.
Step 4: eNodeB indicate the pattern of resource configuration to
D2D UE via control channel (PDCCH)
Embodiments of the present technique can provide an arrangement in
which communications resources are allocated to UEs using a
pre-configured set of resource patterns, which are identified to
UEs using pointers. As with our previously disclosed in
arrangements (European patent application number 15174399.4) the
allocated resource pattern can be determined using conventional
techniques (3GPP TS36.213 14.1.1.1 and 14.1.1.2) and maintained by
the UE over multiple SC-periods. However embodiments of the present
technique can provide an arrangement in which the resource pattern
can be varied across SC-periods by following a pre-defined or
pre-signalled table, for which a pointer is provided. As such, the
same resource blocks do not need to be used in each subframe,
because the pattern may include different resources for subsequent
subframes.
Example Embodiments
Embodiments of the present technique can provide semi-autonomous
resource selection by UEs, which in some examples can act as RSUs.
The controlling eNB can provide a pool of resources
semi-dynamically (for example switching based on load conditions in
each of a multiple of RSUs) and then the RSU can autonomously
schedule data to multiple devices using this pool for a limited
period of time.
Embodiments of the present technique can also provide a scheduled
mode for allocation of (temporary) dedicated resources to UEs in
the coverage area of an RSU. This could be based on, for example, a
number of vehicles currently served in the RSU coverage area, which
would change over time. Therefore, for example, an RSU A would
contain more vehicles than RSU B for a short period of time, during
which RSU A has a larger resource pool assigned, then the resource
allocation can be modified when the vehicles move more towards RSU
B. The RSU then has the responsibility to schedule resources for
the UEs using the autonomous mode. This has the advantage that
there will be contention between the RSUs for resources (no
collisions) because each RSU will have different resources
allocated.
Embodiments of the present technique can provide any D2D UE with
its own resource pool, using an indication identifying a
predetermined pattern of communications resources from a resource
pool. Applications of such embodiments are therefore not limited to
V2X communications, but can be applied to provide a communications
facility to any UE.
As disclosed in [3], a previous proposal identifies scheduling
assignment pools in accordance with a predetermined assignment for
event triggered traffic. However, this proposal does not provide
for an eNB to provide a predetermined pattern of resources which
can be selectable by a UE or assigned to another UE in a group of
UEs where one of those patterns of resources can be allocated to a
UE.
Autonomous Mode
A semi-autonomous resource allocation procedure is illustrated in
one example by the message flow diagram shown in FIG. 19. In FIG.
19, an eNB 1901 first transmits a multiple resource configuration
pattern in a message 1902. The multiple resource pattern
configurations may be provided in a message which indicates a
plurality of sets of resources in accordance with a predetermined
pattern for a predetermined number of sub-frames and therefore
period. The message 1902 is received by a UE 1904, which may in one
example be acting as an RSU 1904. The RUS 1904 is a UE which is
arranged to perform D2D communications with other members of a
group including two other terminals UE2 1906 and UE3 1908.
In a message the RUS 1904 identifies communications resources which
are required to support communications with the vehicle V2X UEs
1906, 1908 and transmits a D2D scheduling request 1910 to the eNB
requesting communications resources to support the D2D
communications with two other V2X UEs 1906, 1908. In response the
eNB 1901 transmits a message 1920 which includes an indication
which identifies a pattern of resource which are allocated to the
RUS 1904. With message exchanges 1922, 1924 the RUS 1904 schedules
resources on a D2D wireless access interface to the UEs 1906, 1908.
If the RUS 1904 identifies that further resource is required or the
amount of resource can be reduced then the RUS 1904 transmits a
message 1930 to the eNB 1901 to request new D2D resources. In
response the eNB 1901 transmits a message 1932, which provides an
indication which identifies different communications resources of a
shared channel for use by the RUS 1904 to use for transmission to
the other D2D terminals in the group 1906, 1908.
For the example shown in FIG. 19, the receiving UEs 1906, 1908 can
be assumed to use a conventional D2D communications interface such
as that specified in 3GPP LTE release 12, PC5 interface. The RUS
1904 sends scheduling control messages addressed to particular UEs
or groups or UEs, followed by data, which the SC messages refer. In
this example, the latency improvement is not present due to being
able to omit an SC period. However, although there is not
significant reduction in a delay for accessing resources, there is
a reduction of scheduling overhead at the eNB 1901. If the RUS 1901
serves multiple UEs, then the RSU 1901 can periodically request an
assignment of multiple resources, for example by including an
estimate of the amount of resources that will be required over a
given period of time. The RSU 1901 is then responsible to manage
those resources, and schedules the UEs which it serves using the
allocated resources. To avoid frequent RRC signalling of resource
pool configuration, the eNB can configure a list of potential
resource pools and then assign those potential resource pools using
a control message transmitted in the PDCCH, for example in response
to a buffer status report and scheduling request transmitted by the
RSU to the eNB.
In order to provide an improvement in latency by reducing a
transmission time for data by a UE, then it is necessary to not
only remove the transmitting UE dependency on the scheduling
channel, but also provide an arrangement in which the receiving UEs
need to monitor the scheduling channel more frequently than
conventional UEs monitoring scheduling channel resources. This is
because a conventional D2D receiver needs to monitor the PSCCH in
order to decode and SC messages which have been transmitted to it.
After receiving the SC message and an allocation of resources on
the shared channel (PSSCH), then the UE can receive the data. If a
UE monitors the PSCCH and receives a SC message, but identifies
that the SC message is directed to another UE, then there is no
need for that UE to receive anything further from the shared
channel resources, and so the UE can save power. However in
accordance with example embodiments of the present technique,
continuous monitoring of the semi-persistent resources may be
needed. The semi-persistent resources are resources on the shared
channel, which have been allocated by an indication identifying
those resources to a UE (such as for example a pointer). For
vehicle based applications this constraint should not limit
operating time, because power consumption in vehicles is not as
much of an issue as with mobile devices such as mobile phones.
Alternatively known starting resources can be used, which occur
more frequently than a regular scheduling channel (providing still
some power saving benefit, but increasing latency). Another
embodiment would be to send the scheduling message on the
scheduling channel from the RSU, but this would eventually be
equivalent to continuous monitoring, since a scheduling control
message would schedule resources in every scheduling period even if
not used.
A similar arrangement can be used for vehicle to vehicle
communication, but an advantage comes when an RSU is allocating
communications resources to a UE. This is because it is expected
that the RSU will always monitor vehicle UE transmissions.
Therefore, one solution to improve latency is simply to remove a
requirement for a vehicle to send an SC message on the PSCCH and
allow immediate transmission. For example, a conventional D2D UE
may monitor the SC with a low frequency in order to reduce power
consumption. However this may not be sufficient to meet reduced
latency requirements. As such for the example of V2X, the rate of
monitoring the SC can be increased in order to reduce the latency.
For example if the rate of monitoring the SC is conventionally
every 40 ms, then for a V2X application, this can be increased to
every 20 ms in order to reduce latency.
Scheduled Resource Selection Mode
Embodiments of the present technique can be arranged to allocate
communications resources in an autonomous mode of operation as
explained for the above mentioned example as disclosed in our
co-pending European patent application number 15174399.4. However
the communications resources are identified as a pre-configured
list of resource patterns, which can be allocated using an
indication identifying a pattern by a control message transmitted
in the PDCCH. The pattern of communications resources may span
multiple SC-periods rather than a single allocation repeated over
multiple SC-periods. The scheduled resource allocation mode
applies, in one example, to a vehicular UE in an area of one or
more RSUs. This is contrast to conventional arrangements (Current
3GPP LTE Release 12) which schedule a pattern of resources within a
single SC-period (see 14.1.1.1 and 14.1.1.2 of TS 36.213).
Furthermore the allocation of communications resources can be
provided to a UE over a period comprising multiple SC-periods. As a
result a signalling overhead caused by repeatedly requesting
resource can be reduced, while also allowing UEs to immediately
transmit in the next available resource, which has already been
allocated. Embodiments of the present technique can provide an
indication of not only a single semi-persistent allocation, but one
or more allocations that vary across SC-periods (e.g. following a
pre-defined or signalled pattern.
If the RSU is the target, it is possible for the UE to transmit
without any SCI information to the RSU, because the RSU knows when
and which type of data is coming from the UE. However this is only
applicable for transmissions from the UEs (vehicles) and the RSU.
In the reverse direction the SCI messages are still required to be
transmitted to the UEs in order to receive data from the RSU.
According to the above explanation, it will be appreciated that
embodiments of the present technique can be used to provide a
signalling reduction. However, in order to improve a latency for
data transmissions one of the following may be applied: A
scheduling period can be configured to be a shorter time than a
currently proposed definition (3GPP LTE Release-12) Receiver can be
configured to monitor known starting resources, which are more
frequent than SC (this is almost the same as just reducing SC
period) A receiver can be configured to monitor all of the time,
instead of relying on the SC. (This is the same as Rel-12 before SC
concept was introduced) UE or RSU is allocated the semi-persistent
resource ahead of actually needing to send data. SC is transmitted
even if there is no data to send. Then, resource is already
reserved and SC is already sent when there is some data to send--so
receiver can detect the transmission. Embodiments of the present
technique can be arranged to reduce latency if the assumption is
that vehicles will always be transmitting a known amount of data,
so that the resource can be semi-persistently allocated over a
longer period of time (e.g. multiple SC-periods).
Embodiments of the present technique can provide for allocating
resource patterns semi-persistently. For example, a small number of
resources could be allocated for every SC-period in order that
delay sensitive traffic can be sent immediately or with as little
delay as possible. In other examples larger blocks of resources can
be transmitted with at longer time periods so that non-delay
sensitive traffic can be sent. The resource pattern can also be
dynamically modified depending on the traffic requirements, load
situation in the cell, etc.
An illustration of scheduled resource selection is provided in FIG.
20. As illustrated in FIG. 20, a plurality of sub-frames referred
to as SC periods 2001 are shown to provide shared channel resources
which are shown within light grey boxes. In accordance with the
present technique the RSU is allocated communication resource in
accordance with a predetermined pattern by the eNB for allocation
to other devices performing V2X communications. The RSU can then
allocate these communication resources according to one or more of
those predetermined patterns to each of the UEs for transmission of
the data. For example as shown in FIG. 20 the first pattern 2002 is
shown with other patterns 2004, 2006, 2008. For the resource 2008 a
UE such as the RSU may transmit a request to the eNB for an
allocation of a new pattern of resources from the eNB at the final
sub-frame 2020 of the semi-persistent period 2022. In a response
message 2025 transmitted from the eNB, the eNB provides a further
allocation of resources in accordance with a predetermined pattern
by sending an indication identifying, such as for example a
pointer, allocating semi-persistent resources for a predetermined
period such as resources within block 2026 or 2028. Accordingly,
resource is allocated and can be selected by terminal devices
within the group in order to provide low latency transmission of a
consistent pattern of data transmissions.
FIG. 20 shown an example whereby the UE has been provided a
semi-persistent resource pattern that can be used in every
SC-period (SC-period corresponds e.g. to the Rel-12 resource
structure). The resources are relatively small, but sufficient to
handle the ongoing delay-sensitive traffic being sent by the
vehicle. Then, the UE determines it has some additional data to
send which does not have as tight a delay requirement. The eNB
allocates a pattern which provides extra resources in every second
SC-period so that the vehicle may transmit this information, while
still transmitting the delay sensitive traffic in every SC-period.
The pattern is selected from a list of pre-defined or
pre-configured (e.g. by broadcast signalling) patterns, only a
pointer is needed using e.g. interpretation of PDCCH.
While the discussions above have been mainly focusing on
semi-persistent allocation of resources, de-allocation or release
of allocated resources can also be managed autonomously by the base
station (or another element) using measurements from terminals
and/or infrastructure nodes without any request from the terminals
or infrastructure nodes. FIG. 21 illustrates an example method of
allocating and de-allocating (releasing) resources, in this case
using the example the allocation in the absence of a resource
allocation requests from terminals (but the same teachings apply
for cases where resources are allocated for two or more allocation
periods in response to an allocation request from the terminal).
First, at S2101, measurements are received for example from one or
more terminals and/or one or more infrastructure nodes. Based on
the measurements, one or more candidate terminal(s)-infrastructure
node(s) associations may be identified (S2102). These associations
can be identified with or without the use of direction information
for the terminals. Then, it can be determined whether any new
resources allocations are required (S2103). If for example the
associations do not include any new terminal-infrastructure node
association and/or if current associations have already resources
allocated for their communications, there may not be a need for any
new resource allocation. In this case, the method can end (or
return to S2101 to process any next measurements). On the other
hand, if resource allocations are deemed appropriate at S2103, the
method moves to S2104 where resources are allocated to the relevant
associations and are communicated to the terminals and/or
infrastructure for any such associations. From S2102, it can also
be determined whether any existing allocation is no longer required
(S2105). For example, a terminal and infrastructure node may have
previously been allocated resources for communicating but their
association may also have been found no longer appropriate at S2102
on the basis of the new measurements (e.g. if the terminal is
moving away from the infrastructure node). In this case, the method
can move to S2106 where a deallocation message may be sent to the
infrastructure nodes and/or terminals. Alternatively, the terminal
may request de-allocation if it considers that it no longer needs
to communicate with an infrastructure node. If however no
de-allocation is deemed required at S2105, the method can end (or
return to S2101 to process any next measurements). While the steps
S2103-S2104 and S2105-S2106 have been represented in parallel in
FIG. 21, in other example they may carried out in a different
order. For example, they may carried out in a sequence in any
suitable order for the four steps.
In some cases, an allocation message received at S2104 may also be
considered as a de-allocation message for the purpose of the step
S2106. For example, if a first set of resources was previously
allocated for a first terminal to communicate with a first
infrastructure node and a new allocation message is sent that
allocation the first set of resources for a second terminal to
communicate with the first infrastructure node, the first terminal
and/or first infrastructure node can also interpret this message as
a de-allocation of the resources for the first terminal-first
infrastructure node association. In such an example, each terminal
may have to read all allocation messages for all terminals to
identify when this situation occurs. In other examples, depending
on the how the allocation and/or de-allocation messages are
identified and read by the terminal in accordance with the
allocation protocol used, it may be considered preferable for each
terminal to only read its own allocation messages. In this case,
the de-allocation messages would be accordingly sent to the
individual terminals rather than relying on the terminal detecting
that its previously allocated resources have now been re-allocated
to a different terminal. Also, some messages may be comprise both
allocation and de-allocation information thereby being used as both
allocation and de-allocation messages.
Accordingly, there has been provided methods, systems, base
stations, terminals and infrastructure nodes which can reduce
delays in transmissions by using direction information for
selecting infrastructure nodes for communicating with terminals
and/or by allocating resources for the infrastructure nodes and
terminals to communicate, in the absence of resources allocation
queries from terminals. Accordingly, the suitability of such
methods, systems, base stations, terminals and infrastructure nodes
for low-delay and low-latency environments can be improved.
While the present disclosure has generally been presented in the
context of V2X or V2X-like environments with RSUs being an example
of infrastructure nodes, the teachings of the present disclosure
are not limited to such environment and may be used in any other
environment where the infrastructure nodes and/or terminals may for
example not be V2X-enabled. Also, whenever a reference is made to a
V2X-enabled unit or node or a V2X environment, a V2X technology
should be understood and combination of one or more of: V2V, V2I,
V2P, V2H or any other type of vehicle-to-something technology and
is not limited to the any currently existing standards.
Also, many of the examples above have been illustrated with a
terminal associated with a vehicle however the same teachings apply
to a terminal which is not associated with any particular object or
person, or associated with a pedestrian, a bicycle, a building or
any other suitable object or person. In the case of an object, the
terminal may be embedded in the object (e.g. a vehicle may comprise
a mobile terminal in which a SIM card can be inserted), may be
associated or paired with the object (e.g. a terminal may set up a
Bluetooth connection with a Bluetooth module of the vehicle) or may
simply be placed in a position wherein it is travelling with the
object without having any particular communicative connection with
the object (e.g. in the pocket of a driver or passenger in a
vehicle).
Also, in the method discussed above, in particular the methods
discussed in respect of FIG. 6 or 13, the steps may be carried by
one or more entities and by any relevant entities. In some example
implementation, some of the steps may be carried out by a terminal
and/or infrastructure nodes while other steps may be carried out by
a base station or yet another element. In other examples, all steps
may be carried out by the same entity, for example the base
station. As an illustration, in examples where direction
information for a terminal is used for allocating resources, the
direction information can be obtained by an element and transmitted
to another one doing the allocation. For example, it may be
obtained by the terminal and/or infrastructure node and may be used
by a base station centralising resource allocation for one or more
infrastructure nodes. In this example, the terminal and/or
infrastructure elements may transmit or communicate the direction
information to the base station for use in the resource
allocation.
Additionally, the method steps discussed herein may be carried out
in any suitable order. For example, steps may be carried out in an
order which differs from an order used in the examples discussed
above or from an order used anywhere else for listing steps (e.g.
in the claims), whenever possible or appropriate. Thus, in some
cases, some steps may be carried out in a different order, or
simultaneously or in the same order. For example, and as previously
mentioned, the de-allocation of resources may be carried out
before, after or while the allocation of resources is carried out.
Also obtaining measurements, obtaining direction information and
identifying (at least) one candidate infrastructure node may be
carried out in a different order and/or simultaneously. For
example, the measurements may be obtained first and used for making
a first infrastructure pre-selection, then direction information
may be obtain to the select the candidate infrastructure node(s).
In other examples, the direction information and measurements may
be obtained in parallel and the candidate infrastructure node
selection may be carried out afterwards.
As used herein, transmitting information or a message to an element
may involve sending one or more messages to the element and may
involve sending part of the information separately from the rest of
the information. The number of "messages" involved may also vary
depending on the layer or granularity considered.
Also, whenever an aspect is disclosed in respect of an apparatus or
system, the teachings are also disclosed for the corresponding
method. Likewise, whenever an aspect is disclosed in respect of a
method, the teachings are also disclosed for any suitable
corresponding apparatus or system.
Whenever the expressions "greater than" or "smaller than" or
equivalent are used herein, it is intended that they discloses both
alternatives "and equal to" and "and not equal to" unless one
alternative is expressly excluded.
It is noteworthy that even though the present disclosure has been
discussed in the context of LTE and/or D2D, its teachings are
applicable to but not limited to LTE or to other 3GPP standards. In
particular, even though the terminology used herein is generally
the same or similar to that of the LTE standards, the teachings are
not limited to the present version of LTE and could apply equally
to any appropriate arrangement not based on LTE and/or compliant
with any other future version of an LTE or 3GPP or other
standard.
Various further aspects and features of the present technique are
defined in the appended claims. Various modifications may be made
to the embodiments hereinbefore described within the scope of the
appended claims. For example although LTE has been presented as an
example application, it will be appreciated that other mobile
communications systems can be used for which the present technique
can be used.
The following numbered clauses define various further aspects and
features of the present technique: Paragraph 1: A method of
transmitting data from a first communications terminal to one or
more second communications terminals, the method comprising
receiving from an infrastructure equipment forming part of a
wireless communications network an indication identifying a
predetermined pattern of communications resources of a wireless
access interface, the wireless access interface providing a
plurality of communications resources divided in time into a time
divided units, and
transmitting the data in some or all of the predetermined pattern
of communications resources to one or more of the second
communications terminals in accordance with device to device
communications, wherein the predetermined pattern of communications
resources is one of a plurality of patterns of communications
resources of the wireless access interface for a plurality of the
time divided units. Paragraph 2. A method according to paragraph 1,
comprising the plurality of predetermined patterns of
communications resources are pre-configured in the first
communications terminal, the second communications terminal and the
infrastructure equipment. Paragraph 3. A method according to
paragraph 1, wherein the method comprising receiving from the
infrastructure, at the first communications device, an indication
of the plurality of predetermined patterns of communications
resources, the indication being transmitted by the infrastructure
equipment for receipt by the first communications terminal and the
one or more second communications terminals. Paragraph 4. A method
according to paragraph 3, wherein the receiving comprises receiving
the indication of the plurality of predetermined patterns of
communications resources from the infrastructure equipment, a
plurality of times, the infrastructure equipment changing the
plurality of predetermined patterns of communications resources
between one time and the next. Paragraph 5. A method according to
any of paragraphs 1 to 4, wherein the pattern of communications
resources identifies different communications resources in
different time divided units. Paragraph 6. A method according to
any of paragraphs 1 to 5, wherein the receiving the identifying
indication identifying of the pattern of communications resources
comprises
receiving a scheduling assignment message from one of the second
communications terminals, the infrastructure equipment having
allocated a plurality of the predetermined patterns for
communications resources to the second communications terminal and
the first or one or more other communications terminals. Paragraph
7. A method of receiving data from a first communications terminal
at a second communications terminal using communications resources
of a wireless access interface, the method comprising
transmitting from the second communications terminal a request for
communications resources to an infrastructure forming part of a
wireless communications network,
receiving from the infrastructure equipment, at the second
communications terminal one or more identifying indications to
communications resources of the wireless access interface, each of
the identifying indications identifying a predetermined pattern of
communications resources of the wireless access interface, divided
in time into a time divided units, for a plurality of the time
divided units,
transmitting from the second communications terminal to the first
communications terminal scheduling message providing an indication
of one or more of the identifying indications, and
receiving at the second communications terminal the data
transmitted by the first communications terminal in the
predetermined pattern of communications resources of the wireless
access interface allocated by the one or more identifying
indications. Paragraph 8. A method according to paragraph 7,
wherein the transmitting the request for communications resources
comprises
determining at the second terminal an amount of communications
resources which are required for the first communications terminal
to transmit the data, and based on the determined communications
resources required, generating the request for communications
resources for transmission to the infrastructure equipment.
Paragraph 9. A method according to paragraph 7 or 8, wherein the
one or more predetermined patterns of communications are
pre-configured in the first communications terminal, the second
communications terminal and the infrastructure equipment. Paragraph
10. A method according to paragraph 7 or 8, wherein the method
comprises
receiving from the infrastructure, at the second communications
device, an indication of the plurality of predetermined patterns of
communications resources, the indication being transmitted by the
infrastructure equipment for receipt by the first communications
terminal and the second communications terminal. Paragraph 11. A
method according to paragraph 10, wherein the receiving comprises
receiving the indication of the plurality of predetermined patterns
of communications resources from the infrastructure equipment, a
plurality of times, the infrastructure equipment changing the
plurality of patterns of communications resources between one time
and the next. Paragraph 12. A method according to any of paragraphs
7 to 11, wherein the pattern of communications resources identifies
different communications resources in different time divided units.
Paragraph 13. A method of allocating communications resources from
an infrastructure equipment forming part of a wireless
communications network, to a communications terminal, the method
comprising
receiving a request for communications resources from the
communications terminal,
in response to the request, transmitting from the infrastructure
equipment, to the communications terminal one or more identifying
indications to communications resources of the wireless access
interface, each of the identifying indications identifying a
predetermined pattern of communications resources of the wireless
access interface, divided in time into a time divided units, for a
plurality of the time divided units. Paragraph 14. A method
according to paragraph 13, wherein the one or more predetermined
patterns of communications are pre-configured in the communications
terminal, and the infrastructure equipment. Paragraph 15. A method
according to paragraph 13 or 14, wherein the method comprises
transmitting from the infrastructure equipment, an indication of
the plurality of predetermined patterns of communications
resources, the indication being transmitted by the infrastructure
equipment for receipt by communications terminals. Paragraph 16. A
method according to paragraph 15, wherein the transmitting the
indication comprises transmitting the indication of the plurality
of predetermined patterns of communications resources from the
infrastructure equipment, a plurality of times, the infrastructure
equipment changing the plurality of predetermined patterns of
communications resources between one time and the next. Paragraph
17. A method according to any of paragraphs 7 to 11, wherein the
predetermined pattern of communications resources identifies
different communications resources in different time divided
units.
REFERENCES
[1] Holma H. and Toskala A., "LTE for UMTS OFDMA and SC-FDMA Based
Radio Access", John Wiley & Sons Limited, January 2010. [2]
TS36.321 V12.5.0, " "Medium Access Control (MAC) Protocol
Specification, 3GPP, March, 2015 [3] European patent application
15174399.4 [4] "Discussion on V2V Scheduling, Resource Pools and
Resource Patterns", Ericsson, 3GPP TSG RAN WG1 Meeting #82bis,
R1-155909
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